<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>fixed</title>
</head>
<style>
    .header{
        height: 200px;
        background-color: saddlebrown;
    }
    .content{
        height: 2000px;
        background-color: salmon;
    }
    .footer{
        height: 200px;
        background-color: seagreen;
    }
    .right{
        height: 100px;
        width: 50px;
        background-color: slateblue;
        position: fixed;
        right: 0;
        top: 100px;
    }
</style>
<body>
    <div class="header"></div>
    <div class="content">
        <div class="right"></div>
    </div>
    <div class="footer"></div>
</body>
</html>